The present art provides dumbbells with adjustable weight. Usually the installing and removing of the additional weights is inconvenient and takes time. Making the removal of the weights easier may come at the sacrifice of the linkage strength between the additional weights to the dumbbell, and therefore may be unsafe, because of the danger that an additional weight will fall from the dumbbell while exercising.
A worm-based mechanism is a known method for installing and removing addable weights.
Using attraction force of magnets is a known method for attaching additional weights.
JP8332245 provides a dumbbell of a weight increasing and decreasing mechanism which can increase and decrease the weight of the dumbbell freely, making use of attraction force of a ferrite magnet, and trains a hand and an arm and promotes circulation of the blood.
None of the known art provides a method which enables installation of additional weights simply by attaching them with magnets and easy removal of the additional weights by rotation, without sacrificing the magnetic linkage force between the additional weights and the dumbbell.
It is therefore desired to have a device and method providing dumbbells with an easy-to-operate mechanism for installing and removing the additional weights, which enables strong and safe linkage between the additional weights to the dumbbell, while providing the comfort of using magnets for attaching the additional weights.